Grout Haze on Limestone

We recently had limestone tiles installed and it's a disaster. We have streaks of grout haze over most of the floor. We've scrubbed and scrubbed, but there's no improvement. I have several questions:

1. Should have it been sealed prior to grouting?
2. What are our options for getting rid of it...polishing/rehoning?
3. Does anyone know the approximate cost to have this done in the Dallas-Fort Worth area?

A sanded grout was used, despite my protests. Will this need to be removed prior to any other work being done? Lastly, this was done by a relative who was supposed to know about these things, so there's no calling my "tile guy" to come back out and fix it.